Critics of the EU ‘Remain’ campaign claim that WhatsApp is being used to organize strategy and tactics because it cannot be subject to Freedom of Information (FoI) requests.

Denials have been issued to the Sun newspaper from the spokesman representing prominent Remain campaigners including Business Minister Sajid Javid, Work and Pensions Secretary Stephen Crabb and Education Minister Nicky Morgan.

A spokesman for Chancellor George Osborne refused to comment after a request by the paper.

“Not only are David Cameron’s taxpayer-funded spin doctors running the ‘In’ campaign, they have now been caught trying to hide their secrets from the public,” Vote Leave chief Matthew Elliott told the Sun Tuesday.

“This is potentially criminal and should be investigated by Sue Gray the Head of Ethics at the Cabinet Office and the Information Commissioner,” he added.

One government source said that the app’s group function was used in the same way for the General Elections in 2015.

Tory MP David Davis, one of the first senior political figures to call for Brexit, said that “attempts to avoid the Freedom of Information Act in what is supposed to be a legitimate activity will lead to scandal and embarrassment.”

He said the Remain campaign would be seen as being “prepared to cheat to win” and that any whiff of scandal would irritate the public.“The government has to learn from the mistakes of Hillary Clinton,” he added.

Democratic presidential candidate Hillary Clinton became embroiled in a scandal in 2015 after it emerged she had used a personal family server for official communications.

The State Department retroactively marked 2,100 of the emails classified and 32,000 were allegedly deleted by Clinton.

Louise Haigh, a Labour MP and shadow digital industries minister, told the paper said she had written to the Information Commissioner urging that the practice be banned or brought under FoI regulations.

She said it was another example of the government trying to “avoid scrutiny and stop us knowing what’s happening with our taxpayer’s money.”